John Hennessy, the computer scientist who heads the Californian university, said such courses were too large to engage and motivate most students successfully. “Two words are wrong in ‘Mooc’: massive and open,” he said.

His comments come amid a rethink by academics and entrepreneurs of a model that many thought would revolutionise education when the idea emerged in 2011. The courses, which promise free access to material being taught in top universities, have drawn millions of users from around the world.

Most people taking online courses at Stanford, which stands at the heart of the Silicon Valley technology community, were simply “not ready for the material at the same level” as the brightest participants, Mr Hennessy said. When the first Mooc came out, 100,000 people signed up but “not even half went to the first lecture, let alone completed all the lectures”, he added.